The present invention relates to a dynamic compression/expansion circuit of the general type disclosed in U.S. Pat. No. 3,969,680. A characteristic of the compression of expansion curve which is "dB linear," i.e. is a linear function of the logarithm of the input amplitude, can be achieved in such a circuit if the setting members used in that system have the same control characteristic in the useful signal path and in the branch path of the circuit.
U.S. Pat. No. 4,278,945 discloses, in connection with such a circuit, the use of linear setting members and a transfer member connected ahead of the setting members and having an exponentional transmission factor. This is of great advantage for the dynamic behavior of the circuit arrangement.
U.S. Pat. No. 3,969,680 also discloses that the interconnection of a plurality of amplifiers with variable transmission factor into a cascade circuit makes possible the achievement of different degrees of compression. If the circuits shown in FIGS. 4 and 6 of that patent are used, it is possible, for example, to achieve a degree of compression of 1:1.5. However, the manufacturing costs for such circuits become considerably higher because they require an additional amplifier and an additional setting member.